Dynamo-electric machine.



outrun STATES PATENT OFFICE.

KARL lAlILY, OF SUIIENICC'IADY, NEW YORK, ASSIGXOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

DYNAMO-E LEGTRIC MACHINE Specification of Letters Patent.

Patented Dec. 17, 1907.

Application filed May 18,1907- Serial No. 374,423.

To all 10710112 it "may concern."

Be it known that I, KARL A. P'AULY, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Dynamo-Electric Machines, of which the following is a specification.

My invention relates to separately-excited generators proyided with means for varying the generator field-strength, so as tovary the voltage impressed onmotors supplied by the generator.

It is well known in the art that ii the voltage supplied to a motor is increased too rapidly, excessive rushes of current are produced, which are objectionable, while if the generator voltage is decreased too rapidly, the motor, if shunt wound or separately excited, will return current to the generator. In order to prevent a too ra id change of the voltage, controlling switc es have been especially arranged heretofore so that their rate of movement is limited. I

My invention consists in making the control wholly automatic by a proper arrange ment of the generator itself. I accomplish this result by providing means for adjusting the magnetic time-lag of the generator,-

that is, the length of time required after a certain increase or decrease of generator field-current for the magnetism of the generator to reach a correspondingly increased or decreased amount. A suitable arrangement for securing the desired result consists in providin a short-circuited Winding on the generator field-pole with a variable resistance included on the short-circuit. This Winding acts as a short-oircuited secondary for the field-flux, and retards any variation in the amount of the flux. In order that the desired adjustment may not be interfered with by .short-circuited currents other than those in the. short-circuited winding itself,

the field magnet should be laminated.

My invention will best be understood by reference to the acompanying drawing, which shows diagrammatically a separatelyexcited generator arranged in accordancewith my invention, for supplying an electric motor.

In the drawing, represents the armature, and B the laminated field structure of the generator. The armature A supplies. the motor-armature O. The line-Wires I) repas to vary the strength of the generator,

field, and consequently the voltage supplied to the motor. A winding F of a few turns is placed on the generator poles, and is short circuited through a variable resistance The purpose of this resistance is to adjust the resistance of the short-circuit. This short-circuit acts to retard a variation in the field-flux, and the amount of the retardation is determined by the resistance of the short-circuit. By a proper adjustment of the resistance f, the desired maximum rate of change in the voltage supplied tothe motor may be secured; so that regardless of the rate at which the resistance e is cut out of or into the field-circuit of the generator, the rate of variation of the voltage supplied to the motor never exceeds a predetermined amount, and excessive rushes of current are avoided.

It will be understood that I have illustrated my invention diagramatically, and that in practice any well-known forms of apparatus may be employed.

What I claim as new and desire to secure by Letters Patent of the United States is,

1. In combination, an electric generator, an electric motor supplied thereby, a separate source of current for the generator field winding, means for varying the lield current of said generator, and means for adjusting the magnetic time-lag of the generator field.

2. In combination, an electric generator, an electric motor supplied thereby, a sepa .rate source of current for the generator field Winding, means for varying the held strength tor supplied thereby, a separate source of means for varying the field-strength of said current for the generator field winding, I generator, a short-circuited winding surmeans for varying the field-strength of said rounding the generator field-poles, and a regenerator, a short-circuited Winding sursistance included in the short-circuit I 5 rounding the generator field-poles, and a re- In witness whereof, I have hereunto set 15.

sistance included in the short-circuit. my hand this 16th day of May, 1907 5. In combination, an electric generator KARL A. PAULY. having laminated field poles, an electric mo- Witnesses: tor supplied thereby, a separate source of BENJAMIN B. HULL,

10 current for the generator field winding, HELEN ORFORD. 

